The manufacture of link sausages is normally undertaken by successively charging individual portions into a casing and then separating them from each other by the twisting-off of the sausage casing. Piston pumps having a controllable stroke or else continuously operating conveying pumps, such as vane pumps, are driven pulsatingly so as successively to discharge uniform portions and serve as sausage filling pumps. The pulsatingly advancing strand of sausage filling is then discharged at the end of a rotatably supported twist-off tube on which the empty sausage casing is received and from which it is pulled between the tube and an annular braking arrangement disposed thereon. The tube and the braking ring are subjected to a short-term rotation between the individual discharge phases of the filling pump, so that the sausage casing is twisted off at the end of the tube from the filling strand which continues to advance and is prevented from rotating. Further conveyance of the sausages and pulling-off of the sausage casing from the tube, as well as the degree of filling of the individual sausage links are therefore determined directly by the velocity of advance of the sausage-filling strand, even though the degree of filling of the sausage casing can be regulated by an adjustment of the frictional force on the braking ring.
This method makes it possible exactly to control the weight of individual sausage links. Length and thickness of the individual sausages are, however, largely dependent on the type of the sausage casing used. In the case of natural intestine casing considerable fluctuations exist with respect to diameter and firmness. In some types of intestine casing increased moisture content and different elasticities of the sausage casing materials lead to diameter fluctuations during filling. Minor diameter fluctuation exist even in synthetic casing. If the filled mass expands upon subsequent cooking the sausage casing can easily burst if filled too tightly. Although the stress placed on the sausage casing can be reduced by an adjustment of the braking ring, the degree of filling and consequently the pressure exerted on the sausage cannot be reduced below preset values, any fluctuations thereof always leading to corresponding changes in the lengths and thickness of the manufactured sausages, when other adjustments are maintained constant. This is particularly disadvantageous if the sausages have to be subsequently packed in a particular fashion, for example in measured quantities, which is economically only feasible if the sausages are of uniform dimensions.
Manufacture of sausage links of uniform length is however known. A continuously driven filling pump produces a sausage-meat strand constantly advancing at a uniform velocity through a stuffing tube and arriving at the end thereof between two conveyor bands with the sausage casing being applied at this location. The empty sausage casing is also rotated uniformly as the conveyed strand advances, while the wrapped sausage strand is prevented from turning. On the conveyor bands there are disposed separation tongues at firmly preset longitudinal intervals which grip the sausage casing externally, constricting it and thus forming a reference point for the rotary tieing off operation.
The length of the sausage links can be only changed by replacing the conveyor bands, the length of the sausages being predetermined by the uniform partitions along the length of the band. The sausages are not, however, of uniform weight since only the filling strand is subdivided longitudinally, the cross-section thereof being determined only approximately by the distance between the conveyor bands. This method is further not suitable for natural intestine sausage casing, but only for synthetic intestine sausage casing having a high degree of firmness and uniform dimensions. The sausage casing is also subjected to considerable external mechanical stresses, particularly since the twist-off operation is continued even if the constricted portion is still disposed between the conveyor bands. Hence high-volume operation can only be obtained if the casing is extremely firm.